FIG. 26 is a block diagram illustrating an overall configuration of a conventional broadcast system. The broadcast system of FIG. 26 is disclosed in Japanese Laid-Open Patent Publication No. 10-155131, and includes a communication terminal apparatus TA1, a server BSV as the broadcast apparatus, a communication terminal apparatus TA2 as the reception apparatus, and a video tape recorder VTR as the unit to be controlled. The communication terminal apparatus TA1 transmits information “recording scheduling request” to the server BSV, which is communicably connected to the communication terminal apparatus TA1 via the Internet INT. In response to the recording scheduling request sent from the communication terminal apparatus TA1, the server BSV transmits personal recording schedule information, as an example of the command, to the communication terminal apparatus TA2 over a text television channel CH. The communication terminal apparatus TA2, capable of receiving televised programs and text, receives a video signal sent over an ordinary broadcast channel, and supplies the received signal to the video tape recorder VTR, which is communicably connected to the communication terminal apparatus TA2. Furthermore, the communication terminal apparatus TA2 sets a recording schedule requested by the communication terminal apparatus TA1 in the video tape recorder VTR according to the personal scheduled recording information sent from the server BSV over the text television channel CH.
Next, technical problems of the conventional broadcast system will be described.
First, while the above publication discloses only one communication terminal apparatus TA2, an actual broadcast system accommodates a number of communication terminal apparatuses TA2. Nevertheless, the server BSV simply sends personal scheduled recording information that arrives at the server BSV while multiplexing it with other signals on the text television channel CH. Therefore, a communication terminal apparatus TA2 may possibly receive personal scheduled recording information which was directed to another communication terminal apparatus TA2. Furthermore, there are a plurality of servers BSV, and they are assigned different text television channels CH. Moreover, the communication terminal apparatus TA2 receives personal scheduled recording information sent over one of the plurality of text television channels CH that is specified by the user. Therefore, in order to reliably perform the scheduled recording, a communication terminal apparatus TA2 needs to be set to a text television channel CH being used by a server BSV when the personal scheduled recording information from the server BSV arrives at the communication terminal apparatus TA2. Therefore, if the appropriate text television channel CH is not selected, the communication terminal apparatus TA2 fails to receive the personal scheduled recording information from the server BSV, thus failing to perform the scheduled recording. As can be seen from the above, the first problem of the conventional broadcast system is that the reception apparatus is likely to fail to accurately receive only those commands that are destined for itself.
Next, while the above publication discloses only one communication terminal apparatus TA1, as with the communication terminal apparatus TA2, personal scheduled recording information arrives at the server BSV from a plurality of communication terminal apparatuses TA1 in an actual broadcast system. Due to the nature of scheduled recording, personal scheduled recording information needs to arrive at the communication terminal apparatus TA2 before the start of the program requested by the communication terminal apparatus TA1. However, the conventional server BSV simply sends personal scheduled recording information that arrives at the server BSV. Therefore, the second problem is that the personal scheduled recording information may not arrive at the communication terminal apparatus TA2 before the start of the program to be recorded by scheduled recording.
Therefore, a first object of the present invention is to provide a broadcast system in which the reception apparatus can receive only those commands that are destined for itself with a higher reliability. Moreover, a second object of the present invention is to provide a broadcast system in which a command sent from the broadcast apparatus arrives at the reception apparatus by a predetermined time.